Impact of Microgravity on Virulence, Antibiotic Resistance and Gene Expression in Beneficial and Pathogenic Microorganisms

Abstract

During space missions, the impact of the space conditions (both microgravity and radiation) on phys-iologic and metabolic aspects of the microbiota of astronauts' bodies should be considered. Changes depend on the mission's duration, types of organisms, and ecology. Reported alterations are related to changes in morphology, growth, gene expression, and physiology of cells, resulting in increased virulence, acid, antibiotic resistance, biofilm formation, secondary metabolism, and microbial muta-tions. Accordingly, recent research indicates the impacts of simulated microgravity on human physi-ology and bacterial characteristics. This paper has reviewed the aspects of microgravity on changes in microbiota, including virulence, antibiotic resistance, and gene expression. Microgravity can under-mine humans and makes influence bacterial pathogenicity. The review of papers shows that some mi-croorganisms showed higher pathogenicity under microgravity conditions. Moreover, sulfamethoxa-zole had the highest resistance among Gram-positive microorganisms, and gentamicin had the highest resistance in Gram-negative bacteria. All antibiotics reviewed under microgravity conditions were robust in both groups of microorganisms compared to the gravity condition. Furthermore, some gene expression was altered in bacteria under microgravity conditions compared to Earth conditions (standard bacterial growth conditions). Changes in microbial behavior under microgravity directly influence astronauts' health conditions, and a detailed analysis of known facts can provide essential information for the selection of appropriate probiotics for these specific cases during the missions and after the recovery processes. Moreover, the study of microorganisms changes in the absence of grav-ity will help to understand the mechanisms of causing diseases on Earth and may be applied in clini-cal practice.

Spaceflight Shifts in Community rRNA Copy Number in the Salivary Microbiome of Astronauts

“…The major stresses on microbial life in space come from microgravity and radiation [28]. Microbes change in response to the stresses of the space environment, including metrics that can harm human health such as biofilm formation, virulence, and antibiotic resistance [25, 28, 29]. Biofilm formation increases bacterial resistance to stresses and can contribute to chronic diseases in humans, such as in the oral cavity [28].…”

Considerations for oral and dental tissues in holistic care during long-haul space flights

“…Further investigating the hypothesis of increased virulence, gene expression and antibiotic resistance of pathogens in simulated microgravity ( Taylor, 2015 ; Senatore et al, 2020 ) is not only important for astronauts but also is significant for understanding and exposing potential alternative mechanisms of disease progression that could be applied to clinical practice on earth ( Salavatifar et al, 2023 ). In simulated microgravity, increased pain scores around the lower jaw especially around the submandibular and sublingual areas during mandibular movements could be related to the lack of resistance from gravity and the potential loss of muscle tone/strength during long term space flights which could eventually lead to changes in occlusion and/or teeth clashing in occlusal positions that are less ideal secondary to the muscular changes.…”